Enrollment, adherence and retention rates among musculoskeletal disorders rehabilitation practitioners in knowledge translation studies: a systematic review and meta-regression

Background Practitioners’ enrollment, adherence, and retention rates influence estimates of effectiveness in knowledge translation (KT) studies and remain important concerns for implementation researchers. This review aimed to systematically summarize the current evidence on feasibility measures as gauged by enrollment, adherence, and retention rates in KT evaluation studies targeting rehabilitation practitioners treating musculoskeletal disorders (MSDs). Methods We searched five electronic databases from the inception to October 2022. We included KT studies that 1) had designs recommended by the Effective Practice and Organisation of Care, 2) targeted rehabilitation practitioners managing patients with MSDs, 3) delivered KT interventions according to the Expert Recommendations for Implementing Change classification, and 4) reported on the feasibility measures (e.g., enrollment, adherence, and retention). Descriptive statistics were conducted to report on study-, practitioners- and intervention-related factors influencing enrollment, adherence, and retention rates. Meta-regression weighted by the sample size of included studies was used to estimate the effect of factors on overall enrollment, adherence, and retention rates. Results Findings from 33 KT studies reported weighted enrolment, adherence, and retention rate of 82% (range: 32%-100%), 74% (range: 44%-100%), and 65% (range: 36%-100%) respectively for both intervention and control groups. Factors positively influencing enrollment, adherence, and retention rates included designing short study period with short duration intervention. Conclusions Intense (e.g., high frequency, short duration) single KT intervention was more appealing for practitioners. Future evaluation studies should clearly report follow-up data, and practitioners’ prior training, Results may not apply to non-MSD healthcare providers. Supplementary Information The online version contains supplementary material available at 10.1186/s43058-024-00585-w.


Contributions to the literature
• Enrolment, adherence, and retention rates ranged between 65 and 82% across the KT studies.• Single intense (e.g., high frequency, short duration) KT intervention was more appealing for practitioners.• Interventions which require less effort and less commitment, and which save participants' time have higher feasibility rates.

Background
Musculoskeletal disorders (MSDs) are one of the most common health conditions experienced worldwide and are costly to the healthcare system [1], with one in six adults (15.6%) reporting chronic MSDs [2].The most common chronic MSDs are osteoarthritis (OA), neck pain (NP), and low back pain (LBP).The World Health Organization estimates that 10% of individuals 60 years or older have significant clinical problems (e.g., functional limitation) that are attributed to OA [3].Likewise, over 80% of the population experience LBP and NP during their lifetime [4][5][6].Importantly, MSDs are associated with a high economic burden globally [7][8][9].In 2010, the Public Health Agency of Canada highlighted that MSDs are associated with a higher economic burden than any other group of diseases, estimated at $37 billion [10].
Rehabilitation practitioners such as physiotherapists (PTs), occupational therapists (OTs), chiropractors (DCs) deliver care to over 11 million Canadians with MSDs, with estimates pointing to an increase to 15 million patients seeking care by 2031 [11].Despite the availability of clinical practice guidelines to inform practice in rehabilitation [12][13][14][15][16], substantial researchpractice gaps among rehabilitation clinicians persist [17][18][19][20].The lack of adherence to recommended care can lead to negative effects on the health outcomes of individuals and communities and lead to inefficient use of limited health care resources [21,22].Knowledge Translation (KT) aims to promote the use of research evidence in healthcare systems [23].Although, KT researchers evaluated the relative effectiveness of different KT interventions in changing healthcare professionals' practice behaviour [24,25], there is uncertainty regarding which KT interventions are likely to be effective in increasing the use of research findings [24,26].As KT interventions are multilevel interventions (e.g., professional, patient, or organizational level), other factors that may have impacted the success of the intervention [27,28].Low participant enrollment, adherence and retention rates (i.e., maintaining clinicians' engagement throughout the course and up to the end of a trial) are major factors that can contribute to the success or failure of KT intervention [29] and influence the estimation of the effectiveness of any intervention [30] in healthcare research [31].Difficulties in participants' enrollment may lead to untimely delays in study initiation, financial burden, and failure to meet enrollment goals (i.e., underpowered trials) resulting in very expensive trials [31].Thus, maximizing enrollment, adherence, and retention rates requires thoughtful planning, and specific strategies embedded in the trial process, and careful monitoring [31].Assessing those rates may help researchers develop more appealing KT interventions that practitioners will more easily accept and sustain into their everyday practices, and improve the design of future trials, and consequently, increase their validity and generalizability [32].Although successful enrollment and retention strategies have been described in clinical trials focusing on adults [33] and children [34], we are not aware of prior reviews having systematically assessed the enrollment, adherence, and retention rates in KT studies.This systematic review aimed to 1) estimate the enrollment, adherence, and retention rates of KT interventions targeting rehabilitation practitioners in charge of patients with MSDs, and 2) identify factors likely to impact on the enrollment, adherence, and retention rates.

Searches
A search strategy was developed in collaboration with a health-sciences librarian to ensure that we captured the maximum number of studies in rehabilitation sciences (Supplementary Material 1: Appendix 1).The search strategy was adapted from a previous review from this team [35], using subject headings (MeSH), keywords, and abstract/text words for MSDs, KT, and rehabilitation, and their synonyms.We searched published literature in scientific journals in the following five databases from the inception to October 2022: OVID MEDLINE, EMBASE, PsycINFO, CINAHL, and Cochrane databases, in English language.All identified citations were exported into End-Note after removing duplicates.

Study inclusion and exclusion criteria
Three independent reviewers (DG, OE, KM) screened the titles and abstracts of studies identified by applying the eligibility criteria.The same reviewers then independently assessed full-text reports of potentially eligible studies.Reviewers met periodically to resolve disagreements and reach a consensus on the eligibility of studies at all stages.

Inclusion criteria
Study design As recommended by the Effective Practice and Organisation of Care (EPOC) systematic reviews [36], we included the following study designs: Randomized Clinical Trials (RCTs), cluster randomized controlled trials, non-randomized controlled trials (NRCTs), or before-and-after studies.
Participants All types of rehabilitation practitioners (e.g., PTs, OTs, Osteopaths, or DCs) managing patients with MSDs.
Intervention KT interventions directed toward rehabilitation practitioners were selected according to the Expert Recommendations for Implementing Change (ERIC) classification [37], which provide comprehensive catalogue of KT interventions that can be used in isolation or combination in implementation research and practice (Supplementary Material 1: Appendix 2).
Outcomes Three feasibility measures were considered: enrollment rate (defined as the proportion of participants who accepted to participate in the study over all eligible participants invited for the study, considering that the number of eligible practitioners was calculated after excluding individuals who did not meet the study's inclusion criteria), adherence rate (defined as the proportion of participants who completed the intervention over all participants who were assigned to the intervention group), and retention rate (defined as the proportion of participants who completed through to the first followup point over the participants who started the study in each group "intervention group [IG] or control group [CG]").

Exclusion criteria
Studies failing to report follow-up data for the participating practitioners were excluded.Studies published in abstract form, as conference proceedings, or protocol forms were also excluded.

Data extraction strategy
A structured extraction sheet was created to collect and extract data from the eligible studies.We extracted data related to study characteristics (i.e., year of publication, country, study design, study duration, number of the study group, study duration, number of followup points, number of outcomes); KT interventions (i.e., type of KT intervention based on ERIC classification, number and duration of the KT interventions, mode of delivery, intensity of the intervention); practitioners (i.e., age, profession and types of MSDs managed; number of practitioners who were approached, eligible to participate, excluded, refused to participate, accepted to participate, and assigned to each study group "if applicable"; number of practitioners who adhered to the KT intervention, and who participated at least in the first follow-up point; and reasons for refusal to participate, and for dropping-out in each study group.The data were extracted by the principal investigator (DG) and reviewed by a second reviewer (OE).

Study quality assessment
Quality assessment was not considered since the focus of this review was on enrollment, adherence, retention rates, and not the effectiveness and effect size of KT interventions likely to be impacted by criteria such as randomization process and missing data [38].

Data synthesis and presentation
Statistical analyses were performed using the Statistical Analysis Systems (SAS version 9.3) [39] guided by two KT experts (AB and SA).Descriptive statistics were conducted to describe variables that possibly affected enrollment, adherence, and retention rates as proportion (%).Moreover, variables were categorized according to their nature and the frequency of data for study characteristics and practitioners-and intervention-related variables described above.
Meta-regression weighted by the sample size [38] of included studies was used to estimate the overall enrollment, adherence, and retention rates.Meta-regression was used since the outcome had a specific range (0-100%).The study, intervention, and practitionersrelated variables aforementioned were used as the factors (i.e., predictors) of the enrollment, adherence, and retention rates.The overall enrollment and retention rates were calculated for intervention and control groups, and the overall adherence rate was estimated for intervention groups only.A meta-regression model was used to assess the correlation between the potential variables and enrollment, adherence, and retention rates.These three rates were treated as continuous variables.A p-value of less than 0.05 was considered as statistically significant.

Descriptive statistics
The search strategy yielded 6088 records after duplicate removal.Screening for titles and abstracts identified 105 potentially eligible articles of which 33 studies met our inclusion criteria  (See Fig. 1.PRISMA flowchart).Table 1 provides a description of the study-practitioners-and KT intervention characteristics of the included studies.

Factors influencing enrollment, adherence, and retention rates
In general, the meta-regression showed that all the aforementioned factors (i.e., variables related to studies, interventions, and practitioners) significantly affected the rates of enrollment, adherence, and retention.All comparisons were significant at P-value < 0.0001 (Table 3).
1) Factors influencing enrollment rate: For studyrelated factors, the enrollment rate was 12% higher in Europe compared to North America.Further, before-and-after studies had about 12% lower enrollment rate compared with controlled trials; implementing a study with more than one study group was associated with a 12% higher enrollment rate, while having more than one follow-up point was associated with an 11% greater enrollment rate.For practitioners-related factors, enrollment rate Fig. 2 Forest plot of the enrollment rates was higher for mixed types of MSDs practitioners by 15% compared to delivering intervention to single type of practitioners (e.g., OTs, PTs, DCs).Also, enrollment rate was higher for practitioners managing BP and NP by 33% and 19%, respectively, compared to practitioners who manage mixed type of MSDs.As for KT intervention-related factors, enrolment rate was lower when employing two to three interventions, or more than three interventions (38% and 16%) higher respectively compared to employing single intervention; but 16% higher when delivering KT intervention online (virtually) compared to in-person; 19% higher when delivering educational meeting for more than 4 h; and 29% higher when conducting the educational meetings more than one time.2) Factors influencing adherence rate: Interestingly, adherence rate for study-related factors was 28% lower in Europe when compared to North America, 13% lower when implementing a study for over 6 months; 11% lower when there was more than one follow-up point; but 27% higher when measuring more than two professional outcomes.For the practitioners-related factors, adherence rate was lower when recruiting mixed types of practitioners, DCs and DOs, OTs, compared to PTs by 32%, 17%, and 5%, respectively.Also, adherence rate was higher for practitioners managing NP by 13%, and lower by Fig. 3 Forest plot of the adherence rates 11% for practitioners managing BP, both compared to practitioners who manage mixed type of MSDs.As for the KT intervention-related factors, adherence rate was 22% lower when employing two to three interventions; 32% lower when delivering KT intervention online compared to in-person mode; but 16% greater when implementing a meeting length more than 4 h; 12% higher when conducting the educational meetings more than one time; and 29% higher when delivering the KT intervention for a long period (e.g., 1 month up to 6 months).3) Factors influencing retention rate: Similarly for study-related factors, retention rate was 17% higher in other countries (i.e., Australia) compared to North America.Retention rate was 31% lower when in before-and-after study compared to controlled trials; 22% lower when implementing a study for over 6 months; but 31% greater when implementing a study in more than one study group.The retention rate was also 28% lower when hav-ing more than one follow-up point; and 14% higher when measuring more than two professional outcomes.Concerning the practitioners-related factors, retention rate was 16% higher when recruiting OTs, but lower 15% when recruiting mixed types of MSKs practitioners compared to recruiting PTs.Also, retention rate was lower for practitioners managing BP by 12% compared to practitioners who manage mixed type of MSDs.As for the KT intervention-related factors, retention rate was 31% and 13% lower when employing two to three interventions or more than three interventions vs employing a single intervention, respectively.Compared to in-person mode of delivery, retention rate was also 35% lower for online KT interventions, but 15% higher for postal dissemination.Retention rate was 13% greater when conducting the educational meetings more than one time and 29% higher when delivering the KT intervention for a long period (e.g., 1 month up to 6 months).

Discussion
To our knowledge, this is the first review estimating the enrolment, adherence, and retention rates of KT interventions targeting rehabilitation practitioners managing patients with MSDs.Results of the current review showed high enrolment rate (82%) in KT studies, and relatively high adherence (74%) and retention rates (65%) across studies.This review supported that designing a study with more than one group of practitioners with a controlled arm is associated with higher feasibility rates.Similar findings were reported by Lixin Song et al. [74] when examining the enrollment and retention rates clinical trials of patients with cancer and their caregivers.Studies of shorter period (less than 6 months) with only one follow-up point with multiple outcome measures were associated with higher feasibility rates.These findings are possibly explained by the difficulties for practitioners to commit to their regular work schedule over a long period, thereby limiting their ability to report outcomes over multiple follow-up points.
We uncovered a number of appealing interventionrelated features for rehabilitation practitioners that seems to promote all three feasibility measures.First, employing a single intervention for a short period of time (1 month up to 6 months) is significantly associated with the higher rates.Systematic reviews of KT studies have suggested that single active KT interventions may be as effective as multi-component intervention in changing practice [26,[75][76][77].The complexity of interventions may dampen the key messages and diminish the ability of practitioners to digest the presented information [78].Previous studies reported a higher enrollment rate when recruiting participants for studies with ≥ 4 months intervention duration [74,79].Second, implementing a long educational meeting (more than 4 h) for more than one time is associated with higher rates; this possibly means that practitioners prefer for instance to concentrate on a full day workshop offered multiple times (i.e., long-term engagement), instead of having several short meetings during their busy working day when being exposed to the content of the KT intervention.Lastly, delivering KT intervention virtually or in-person mode provided mixed results with virtual mode being associated with a higher enrolment rate, whereas in-person mode was associated with greater adherence and retention rates; these findings support that online interventions could be considered as time and effort saving modes of delivery.Feasibility rates don't seem to be harmonically affected by the practitioners' profession or the type of MSDs they manage.Considering those intervention-related factors may secure higher practitioners' involvement in the KT studies for longer duration.

Strengths and limitations
This systematic review followed rigorous methodology, including a comprehensive search strategy developed in collaboration with a medical science librarian, the use of multiple electronic databases.However, this review is not without limitations.First, several studies failed to report on the number of practitioners who were eligible to participate in the study.Second, other variables that could be influential, such as practitioners' educational backgrounds and practitioners' beliefs in KT interventions, could not be included in the analyses as sufficient information on these variables was not available.Third, assessing the impact of each type of KT interventions separately on the feasibility rates was not possible due to the overlapping of the KT interventions in each study.Fourth, the included studies fail to reported the number of participants received each KT intervention separately.Finally, this review was restricted to KT interventions targeting MSDs rehabilitation practitioners only.Thus results may not apply to other healthcare disciplines.

Conclusion
This systematic review identified 33 studies employing KT interventions to promote the uptake of research evidence by MSDs rehabilitation practitioners, including PTs, OTs, DCs, and osteopaths.Findings showed that enrolment, adherence, and retention rates ranged between 65 and 82% across the KT studies.Moreover, this review showed that single intense (e.g., high frequency, short duration) KT intervention was more appealing for practitioners.Interventions which require less effort and less commitment, and which save participants' time have higher feasibility rates.KT researchers should consider the time required from healthcare practitioners to participate in a KT studies to maximize the feasibility rates, and consequently increase the generalizability of their findings.

Fig. 1
Fig. 1 PRISMA flow diagram representing the process of study selection

Fig. 4
Fig. 4 Forest plot of the retention rates

Table 2
Types of KT intervention classified according to ERIC classification OC Ongoing Consultation, CTA Centralize Technical Assistance, DvEM Developing Educational Materials, CLC Creating a Learning Collaborative, PCS Providing Clinical Supervision, IPEA Intervening with Patients to Enhance Adherence, PPAP Preparing Patients to be Active Participants, LCD Local consensus discussions, COT Conducting Ongoing Training, MM Mass media EM Educational Meetings, DEM Distribution of Educational Materials, AF Audit and Feedback, LOL Local Opinion Leaders, RD Reminders, FT Facilitation, OV Outreach Visits,

Table 3
Meta-regression of factors influencing rates of enrollment, adherence and retention CI Confidence Interval, CTs Controlled Trials, DCs Chiropractors, PTs Physiotherapists, OTs Occupational Therapists, ref Reference Category, / Missing or Not Applicable